2000 - present Professor of Physics, University of California, Santa Cruz 1989 - present Professor of Physics, Rutgers University 1986 - 1989 Professor of Phy sics, University of Californi a, Santa Cruz 1980 - 1986 Associate Professor of Physics , Tel Aviv University 1982 - 19 84 Visiting Associate Pro fessor of Physics, Stanford University and Stanford Linear Accelerator, Member Institute for Advanced Study, Princeton 1977 - 1980 Senior Lecturer w ith tenure, Tel Aviv University 1975 - 19 77 Lecturer, Tel Aviv University